A little more, from a genealogical site:

"...came across the countess in Great Britain, where she first
published the majority of her cookbooks and greatly advanced the fame
of Creole cuisine. Her books are now kept by the Bodleian Library at
Oxford University. One of her book jackets claims that her title was an
ancient Spanish one and that she was born and raised in New Orleans,
where she learned her art from distinguished professional chefs and
maids. By 1931, however, she had moved to England, where her books were
for the greater part published. By 1954, she was married to Ellert
Forbes, who assisted with the editing of her books."

source:http://www.nola.com/ancestors/archiv.../la082999.html